PhysicsLAB: Archimedes Principle #1

Refer to the following information for the next five questions.

Consider a balloon filled with 1 liter of water (1000 cm³) in equilibrium in a container of water, as shown in Figure 1.

a. What is the mass of the 1 liter of water?

b. What is the weight of the 1 liter of water?

c. What is the weight of water displaced by the balloon?

d. What is the buoyant force on the balloon?

e. Discuss with your partner where these two vectors should be drawn on Figure 1: one for the weight of the balloon and the other for the buoyant force that acts on it.

How do the size and directions of your vectors compare?

Refer to the following information for the next five questions.

As a thought experiment, pretend we could remove the water from the balloon but still have it remain the same size of 1 liter. Then inside the balloon is a vacuum.

a. What is the mass of the liter of nothing?

b. What Is the weight of the liter of nothing?

c. What is the weight of water displaced by the massless balloon?

d. What is the buoyant force on the massless balloon?

e. In which direction would the massless balloon be accelerated?

Refer to the following information for the next six questions.

Assume the balloon is replaced by a 0.5-kilogram piece of wood that has exactly the same volume (1000 cm³), as shown in Figure 2. The wood is held in the same submerged position beneath the surface of the water.

a. What volume of water is displaced by the wood?

b. What is the mass of the water displaced by the wood?

c. What is the weight of the water displaced by the wood?

d. How much buoyant force does the surrounding water exert on the wood?

e. When the hand is removed, what is the net force on the wood?

f. In which direction does the wood accelerate when released?

Refer to the following information for the next six questions.

Repeat parts a through f in the previous question for a 5-kg rock that has the same volume (1000 cm³), as shown in Figure 3. Assume the rock is suspended in the container of water by a string.

a. What volume of water is displaced by the rock?

b. What is the mass of the water displaced by the rock?

c. What is the weight of the water displaced by the rock?

d. How much buoyant force does the surrounding water exert on the rock?

e. When the hand is removed, what is the net force on the rock?

f. In which direction does the rock accelerate when released?